Artifacts of Lore #2: Mjolnir

Mjolnir is the Hammer of Thor, a mighty artifact wielded by the thunder god himself. Nicknamed “Mountain Crusher”, Mjolnir was created (like Odin's spear Gungnir) by dwarves tasked with creating precious items for the gods. It is said that when Thor wields Mjolnir in battle against the giants, it can be heard for many miles as the sound of crashing thunder.

Besides being mighty in battle, Mjolnir is unbreakable; in addition, it returns to Thor's hand after being thrown, and can be made smaller for ease of carrying. In combat, it crashes like thunder and crackles with lightning.

I always kinda saw that as Thor having ranged weapon attacks rather than a property of the item itself; technically someone else shouldn't even be able to wield it (although that's no fun in D&D, so I didn't use that aspect). As a magic weapon, it autimatically returns to his hand.

It's easy enough to give it a range attack, though. I've slipped the range keyword in there if you want to check it out again.